This invention relates to poppet dampers or valves, and particularly to isolation dampers which are used to control the flow of particulate laden gases to a baghouse or series of baghouses containing fabric filter collectors. The typical dampers used in such a situation include the round flat plate poppet type, and round or rectangular butterfly types.
The more generally accepted baghouse isolation damper design is the round, flat plate poppet type, positioned either vertically or horizontally and operated (open/close/open) axially (in a linear direction) by an actuating device. This actuating device can be a manual gear type operator; a linear type pneumatic or hydraulic cylinder or a linear type electric motor driven actuator. The poppet type damper has become the standard design because of its ability to affect a gas tight seal, its simplicity of design and construction, and its high degree of operational reliability. The butterfly types, either rectangular or round, are used where tight sealing is not a critical requirement. Generally, an isolation damper is used to take off a percentage of the total gas in an inlet manifold and direct it to a particular baghouse rather than to divert 100% of the flow. Examples of devices useful for 100% diversion include U.S. Pat. Nos. 3,147,773, 3,116,756, 3,270,775, and 3,537,240.
One factor that is of great significance in the design of a particulate handling system, such as a flyash collection system for a boiler, is the pressure drop in the system. Some systems are of such a massive size that a pressure drop improvement of just one inch of water over the expected life of a plant can reduce the operating cost by $100-500,000. Thus, even a very small improvement in pressure drop can be very important.